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sav wui� � � <br />F�om: Schradx, [ b�Mvus.wa.us] <br />S� Thuraday, 14,19� •28 PM <br />To: 'Kaveh fminian'• Tom IOrurtpn';'Jon 3iu';'SEsw Pfeilfer <br />Ce: 'Ewrett - SEsve �ANler; 'Midal Ro�aans'; Tacan� - Gp Ps�raon'; 'Jim Shnton'; 'Ken <br />Crlson ;'John MlnaEo'; ',I�Y KeNsY ;'Lar►Y Meddhp - Re�Mon ; Foumier. Art <br />Subj�et: two issues w/ pt desfpn d oonstruction <br />Do�'t know how mix:h youYe seen this � but Mn's �ortis fnlo on a <br />coupls posRtensioninp bsues IYe sncoun . Maybs you'ro aMraro of aN <br />of thb atuH. <br />Ws hwe ap�t thaCs undx oonstructfon usiny HVAC duct fn e 712" PT <br />sleb 1ar rosfds-n I floon. Ths oontractor is Ledcor out of Gneds. I've <br />talked wilh a oumEsr of psopw about this bsue. HVAC duct has been used in <br />mfa rsin/aced slabs a yrs�er thidcnsu in tha vancarvx aea a lot, but <br />ua In PT sl�bs ha bNn bmited in lhb a�. I undsrsWid Mat sNr�r <br />proJscls In Swtlb aro sNher in ths detian or oonstruclion ph�N ft <br />appsars that 712" b lhe thinnest sl�b �ato aon wak wNh iMs sysaem when <br />Bslisv� hom�vraNdnp tlN deck�lEs a%k Ior�UonNrork�peefts�s. <br />oomol� � nder ths�s d��d��ucts a�ro � 5c <br />bMt H�y 'ro above ths middk of ths slab io �Ilow beltx �t2s 12". IPs <br />P��f under them� as iodc poeksts or voids aro poasibb. eottom mild <br />atssl thoup hout end mesh ovet thstop of the ducta to about a foot eMher <br />side b�pob�bly needed. Al�o the duds should ba kept out of high shear <br />�npNivs mmortbnt ropions, ao near the middk third oi a apen and away <br />We abo just hada ap p�ropo.al to uae pertlal prostres:inp in the sl�bs for the <br />s� �phom PT. It b not sbasicallvy amddtss �sed i�tlieaACINBC or the <br />pecifcaI <br />IBC but ft appsars tlwt ths in ud atry is headed in the directlon of romovinp <br />ths �T stroa Iimib cumently in the code, similer to the desipn of a mNd <br />ateM slab. I bNf�w Bob Mast rocendy proposed this chanpe. Thhappsers <br />to be an eMeclfw qMem whero cracking is not a major considerafbn for <br />cortosbn or appe�nnce, and the code does not provent its uss. Thero is <br />wordiny about an altemate design. <br />Hope thaYs helpiul. Let ma know if you have comments or expetisnce with <br />theseisauea. <br />Thanks. <br />Gregg Schrader <br />